Fingerprints are one of many forms of biometrics used to identify individuals and verify their identities. Fingerprint readers have been gradually incorporated with many electronic products as password security protections such as access control system, and the combination devices with vehicle, notebook computers, mobile phones, flash drives, mouse and keyboard etc. The analysis of fingerprints for matching purposes generally requires the comparison of several features of the print pattern. These include patterns, which are aggregate characteristics of ridges, split, split and join and minutia points, which are unique features found within the patterns.
Fingerprint reader generally has an optical, capacitive, ultrasonic and thermal induction type, etc. Optical fingerprint reader belongs to the total reflection type, it commonly includes an optical module and an optical imaging apparatus.
It is difficult and complicated to assemble the total reflection type fingerprint reader. Since people must precisely arrange the optical module and an optical imaging apparatus in the assembly process in order to effectively adjust the angle of the light incident and emergent beams. Furthermore, the emitting source of optical type fingerprint reader is usually a point light source, it easily leads to the blurred image due to uneven distribution of light.